Traction system.



PATENTED MAY 19,1903.

E. L. K. F. KAHLENBBRG.

TRACTION SYSTEM.

APPLICATION FILED FEB. 27, 1899.

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PATENTED MAY 19, 1903.

E. L. K. F. KAHLENBERG. TRACTION SYSTEM.

APPLIUATIQN FILED T11R27, 1899. H0 MODEL. 2 $HEETS-SHBET 2.

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UNITED STATES Patented May 19, 1903.

PATENT OFFICE.

ERNST LUDWIG KARL FRIEDRICH KAI'ILENBERG, OF CIIARLOTTENBURG, NEAR BERLIN, GERMANY, ASSIGNOR TO SIEMENS & HALSKE ELECTRIC COMPANY OF AMERICA, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TRACTION SYSTEM.

SPECIFICATION forming part of Letters Patent No. 728,581, dated May 19, 1903.

Application filed February 27,1899. Serial No. 707,029. No model.)

To all whom it may concern:

Be it known that I, ERNST LUDWIG KARL FRIEDRICH KAHLENBERG, a subject of the German Emperor, residing at Charlottenburg, near Berlin, Germany, have invented a certain new and useful Improvement in Traction Systems, (Case No. 179,) of which the following is a full, clear, concise, and exact description.

My invention relates to control systems for alternating-current induction motors, and has for its object to provide a simple system especially adapted for effecting the control of the propelling-motors on an electricallyoperated train.

In the system which I have devised the motors on the several motor-cars are provided with resistances of predetermined value permanently included in the armature-circuits, and the field-windings of the several motors are connected to a system of conductors extending throughout the train, this system being connected to the source of supply through a tension-regulator, which may be located at any desired point, although it is preferably placed at the front end of the train. The employment of such a system enables me to obtain from the propellingmotors a large torque at starting without seriously reducing the efficiency at full speed and provides for the complete control of all the motors on the train without the complicated train-wiring, which would be required with those systems in which resistances in circuit with the motor-armatures are varied to obtain therequisite speed regulation or those in which the regulation is obtained by changing the connections of the field-windings from star to triangle connection, and vice versa'.

My invention will be more readily understood by reference to the following description, taken in connection with the accompanying drawings, while its scope will be pointed out in the appended claims.

Referring to the drawings, Figure 1 shows the two cars of an electrically-propelled train equipped in accordance with my invention, and Fig. 2 sets forth with more precision the circuits and apparatus employed therein.

ticular system which I have chosen for illustration makes use of motors of the three-phase type. These motors are indicated at b, b b and h, each motor being associated with one of the axles of the cars A and A The field-windings of the motors are connected in parallel relation to the system of conductors c c 0 which extends throughout the length of the train, connections being made between the cars by means of flexible conductors or any other well-known devices. Each of the propelling-motors is provided with a resistance mounted on the same car therewith, and these resistances (indicated on the drawings by d, d d and 61 are permanently connected in circuit with the armatures of the respective motors through suitable contact-brushes and collecting-rings. As shown in the drawings, the car A is at the head of the train, and this car is provided at its forward end with the controlling-switch e and a suitable appliance f for controlling the tension of the current supplied to the field-windings of the motors. The means for regulating the tension of the current may evidently be of anydesired type, and in Fig. 2 I have diagrammatically illustrated one of the appliances which may be used for this purpose. As shown in this figure, the tension-regulating means comprises a plurality of primary windings f, f, andf which are respectively connected at one end in star arrangement, their other terminals being connected to the supply-conductors through the contacts of the controlling-switch e. Each of the primary windings f, f and f has a secondary winding g g g in inductive relation thereto, and each of the said secondary windings is connected in series relation with one of the conductors of the supply-circuit. The conductors of the system through which current is supplied to the field-windings of the motors are each connected to one of the secondary windings through a movable contact-point f, by movement of which the number of turns of the secondary winding included in circuit with the source of supply is varied.

It is of course necessary in any given system to calculate the value of the resistances connected in circuit with the armatures of the several motors, this value being dependent upon the conditions of operation which are to be met with in the particular system, such as the gradients of the road and the tension of the supply-circuit. The employment of the permanently-connected resistance enables the motors to be started with a maximum torque, and even when a relatively large amount of resistance is employed it is found that highly satisfactory conditions of operation are secured, for the loss of energy due to the resistance in the armature-circuit of an induction-motor varies in direct proportion to the slip or fall in speed from synchronism. The resistances which are required for securing the necessary torque at starting may therefore be left in circuit with the armature-winding after normal speed is obtained without any considerable reduction in the efficiency of the motors. The torque that may be obtained from any given motor is, however, dependent upon the tension at the motor-terminals, it being well known that the torque of a motor of this class varies Within certain limits as the square of the applied tension. By increasing the tension at starting it is therefore possible, otherthings being equal, to obtain a very greatly increased torque at starting. By employing the arrangement of apparatus and the system of connections herein shown and described it is therefore possible to secure a variation in torque which is admirably suited to the needs of a traction system Without the employment of a complicated system of trainconductors.

In starting the train the motorman operates the tension-regulating device to give the desired starting torque and after getting his train under headway adjusts the movable contacts f until the tension atthe motor'terminals is brought to the point desired for running conditions. Thus instead of cutting in or out resistance as the requirements of the motors vary the motorman is able to effect the control of the propelling-motors by a simple manipulation of the tension-controlling device, thereby securing a decided simplification of the circuit arrangements and the controlling apparatus employed on the cars.

Various modifications may be made in the system herein shown and described without departing from the spirit and scope of my invention, and I do not desire to be understood as limiting the same to the precise appliance and circuit connections herein set forth.

Having now described my invention and indicated apparatus suitable for practicing the same, what I claim as new, and. desire to secure by Letters Patent of the United States,

1. In a traction system, the combination with a motor-car provided with an inductionmotor, of a resistance of predetermined value mounted on the same car with the motor for which it is designed and permanently included in circuit with the armature thereof, a source of cnrrent-supply for normally operating said induction-motor, and means associated with said current-supply for increasing the pressure thereof when the car requires more than the normal amount of torque to propel the same, substantially as described.

2. In a traction system, the combination With a motor-car, of an induction motor mounted upon the same, a fixed resistance mounted upon the same car with the motor, which resistance is adapted, when the motor is starting, to prevent an abnormal flow of current of displaced phase through the motor-windings, the resistance being of such value as not to interfere with the successful operation of the motor after the same has reached speed, a source of current for normally operating said induction-motor, and means for increasing the pressure of the said source of current, substantially as described.

In witness whereof I hereunto subscribe my name this 3d day of February, A. D. 1899.

ERNST LUDWIG KARL FRIEDRICH KAI'ILENBERG.

Witnesses:

HENRY HASPER, WM. MAYNER. 

